Carbon-Ion Irradiation Suppresses Migration and Invasiveness of Human Pancreatic Carcinoma Cells MIAPaCa-2 via Rac1 and RhoA Degradation
Carbon-Ion Irradiation Suppresses Migration and Invasiveness of Human Pancreatic Carcinoma Cells MIAPaCa-2 via Rac1 and RhoA Degradation
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DOI：
10.1016/j.ijrobp.2015.05.009
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发表时间：
2015-09-01
影响因子：
7
通讯作者：
Imai, Takashi
中科院分区：
文献类型：
--
作者：
Fujita, Mayumi;Imadome, Kaori;Imai, Takashi
目的：方法和材料：人胰腺癌细胞MIAPaCa-2、AsPC-1和BxPC-3分别经X射线（4戈伊）或C-离子（0.5、1、2或4戈伊）照射，2天后测定其迁移和侵袭能力。三磷酸鸟苷（GTP）结合的Rac 1和RhoA的水平通过有或没有蛋白酶体抑制剂的主动GTP酶下拉测定来确定，并且通过免疫沉淀来检查E3泛素连接酶与GTP结合的Rac 1的结合。碳离子辐射降低了GTP结合的Rac 1和RhoA的水平，这是细胞运动的两个主要调节因子，在MIAPaCa-2细胞中，GTP结合的Rac 1在AsPC-1和BxPC-3细胞中。蛋白酶体抑制逆转的效果，表明C-离子照射诱导Rac 1和RhoA降解通过泛素（Ub）-蛋白酶体途径。C-Ione诱导MIAPaCa-2细胞产生直接靶向Rac 1的E3 Ub连接酶X连锁凋亡抑制蛋白（XIAP），并与C-Ione诱导的Rac 1共沉淀，这与Rac 1的泛素化有关。短干扰RNA介导的XIAP敲低可恢复C离子辐射降低的细胞迁移和侵袭，表明XIAP参与了C离子诱导的细胞运动抑制。与X射线照射相比，C离子处理通过Ub介导的蛋白酶体降解抑制MIAPaCa-2细胞中Rac 1和RhoA的活性以及AsPC-1和BxPC-3细胞中Rac 1的活性，从而阻断这些胰腺癌细胞的运动性。(C)2015年，作者。由爱思唯尔公司出版
Purpose: To investigate the mechanisms underlying the inhibition of cancer cell migration and invasion by carbon (C)-ion irradiation.Methods and Materials: Human pancreatic cancer cells MIAPaCa-2, AsPC-1, and BxPC-3 were treated by x-ray (4 Gy) or C-ion (0.5, 1, 2, or 4 Gy) irradiation, and their migration and invasion were assessed 2 days later. The levels of guanosine triphosphate (GTP)-bound Rac1 and RhoA were determined by the active GTPase pull-down assay with or without a proteasome inhibitor, and the binding of E3 ubiquitin ligase to GTP-bound Rac1 was examined by immunoprecipitation.Results: Carbon-ion irradiation reduced the levels of GTP-bound Rac1 and RhoA, 2 major regulators of cell motility, in MIAPaCa-2 cells and GTP-bound Rac1 in AsPC-1 and BxPC-3 cells. Proteasome inhibition reversed the effect, indicating that C-ion irradiation induced Rac1 and RhoA degradation via the ubiquitin (Ub)-proteasome pathway. E3 Ub ligase X-linked inhibitor of apoptosis protein (XIAP), which directly targets Rac1, was selectively induced in C-ioneirradiated MIAPaCa-2 cells and co-precipitated with GTP-bound Rac1 in C-ioneirradiated cells, which was associated with Rac1 ubiquitination. Cell migration and invasion reduced by C-ion radiation were restored by short interfering RNA-mediated XIAP knockdown, indicating that XIAP is involved in C-ion-induced inhibition of cell motility.Conclusion: In contrast to x-ray irradiation, C-ion treatment inhibited the activity of Rac1 and RhoA in MIAPaCa-2 cells and Rac1 in AsPC-1 and BxPC-3 cells via Ub-mediated proteasomal degradation, thereby blocking the motility of these pancreatic cancer cells. (C) 2015 The Authors. Published by Elsevier Inc.